1. Field of the Invention
The present invention relates to an improved data separator for use with magnetic or optical data storage devices such as a hard disk, floppy disk, or the like.
2. Prior Art
Digital data is commonly stored for subsequent processing in a microprocessor or other form of data processor in a variety of magnetic or optical data storage devices. One of the more commonly used medium for data storage is a floppy disk on which data is typically stored in one of several formats, such as self-clocking Manchester codes that include MFM, FM, and others. The data stored on a floppy disk in any one of these formats includes both data and clock pulses combined in an encoded data stream. In order for the data from the floppy disk to be useful in the data processor, the data must be separated from the clock, and encoded data pulses from the disk must be synchronized with respect to a half-bit clock or window.
U.S. Pat. No. 4,845,575, assigned to the assignee of this application, discloses a floppy disk data separator that employs a digital delay line to achieve the desired data and clock synchronization. That data separator has proven to be highly effective at current, relatively low data rates of up to 500 mHz to 1 mHz. However, at higher data rates, which are now coming into use, of between 1.0 mHz and 2.5 mHz, the required reduced quantization error makes it unfeasible to employ a digital delay line, which cannot provide the needed accuracy. The needed higher accuracy can be achieved by the use of an analog delay line but the high cost of an analog delay line that is capable of providing the requisite high precision at the higher data rates makes that an impractical design choice. There thus exists the need for a data separator capable of achieving accurate and reliable data separation that can be utilized at higher data rates at a lower cost and with less space required in an integrated circuit or circuit board.
It is accordingly an object of the present invention to provide a data separator capable of reliable operation at high frequencies.
It is another object of the invention to provide a data separator that does not require the use of a digital or analog delay line.
It is a further object of the invention to provide a data separator capable of operating at high frequencies and which is still relatively low in cost.
It is yet a further object of the invention to provide a data separator which operates with the precision of a data separator that employs an analog delay line but at a much lower cost and of a reduced size.